Real Madrid is looking for a new left-back. With the transfer window opening up soon, there is plenty opportunity for Jose Mourinho to find a replacement for Marcelo and Fabio Coentrao.

Before anyone overreacts, let's realize something.

You might be asking yourself why Real Madrid would waste money on a position that, when everyone is healthy and in form, is log-jammed. Well, fair point, but that's exactly the point.

Soccer, like any sport, is full of injuries and poor spells of player performance, which is the unfortunate inevitability every team must face.

Left-back has been particularly concerning so far this season for Real Madrid.

They lost Marcelo back in early October when he broke his foot training with Brazil. Fabio Coentrao, his backup, was sidelined with a groin injury until recently.

It's only natural, then, that Jose Mourinho has put signing a new defender on Madrid's transfer priorities. Sure, Coentrao has been filling in nicely since his return, and Marcelo will eventually be back, but as their injuries show, you must be prepared to rotate the squad.

Most would expect the club to open up the bank for every transfer, and most of the players linked usually require it, but they can benefit from under the radar signings as well.

Taking all that into account, these are four players (not the only four players) Real should look at as replacements.

1. Gareth Bale

Jamie McDonald/Getty ImagesBale is the ideal replacement

Let's get the most obvious out of the way. Gareth Bale is Jose Mourinho's ideal candidate.

Mourinho has been coveting Bale for a while now and recently has stepped up his efforts to bring in the talented Welshman, as Mirror Football reports. In January, Real is preparing to offer Fabio Coentrao as part of a deal to cut Tottenham's transfer price for Bale.

In Bale, Jose Mourinho would get the exact player he lost back in October. He is a lot like Marcelo.They are both defenders, or were in Bale's case, who are known more for their offense than their defense.

In fact, the one knock on Bale would probably be his defense. It's probably the reason he plays predominantly as a winger now. That hasn't stopped Marcelo though, so I don't see it being a problem for Bale.

Bale is also a better fit than Marcelo. Yeah, that's going to upset some people, but I'm not enamored with Marcelo like (apparently) the rest of the world.

They both attack well and aren't the greatest of defenders. Bale is more of a physical presence and not nearly as reckless as Marcelo.

Also, Bale signing doesn't mean the end of Marcelo at Real. Mourinho could very well keep them both around and rotate them as he sees fit.

Whatever the case, Bale is high on their list, and it's easy to see why.

2. Ashley Cole

Shaun Botterill/Getty ImagesAshley Cole is not the first choice, but he'd be the best

Ashley Cole is the perfect candidate to take over left-back at Real Madrid.

For starters, he may be the easiest to acquire. His current contract with Chelsea runs out in the summer, and due to Chelsea's policy on over-aged players, he will not be signing an extension. Rather than wait till the summer, Real could snag Cole at a bargain rate.

He also happens to be the best left-back in the world. Or maybe best all-around is a better term for it.

He's not a prolific attacker, but he's very skilled and is constantly involved in his team's attack. He does, however, excel where most players at this position seem not to.

Somewhere along the way defense has become an afterthought for left-backs. They now mostly focus on joining the attacking buildup, but Cole is the exception.

In addition to his good attacking sense, he is also a high-quality defender. The fact that he can attack and defend are what, obviously, make him the perfect candidate.

He has been rumored to be heading to Paris Saint-Germain, as the Daily Mail noted, but most of that discussion has him going in the summer after his contract expires.

3. Leighton Baines

Jan Kruger/Getty ImagesBaines is a lot like Ashley Cole and would be a great signing

Leighton Baines, much like Ashley Cole, is already linked with a move elsewhere (Manchester United, according to The Daily Mail) but would be a great fit at Madrid.

Baines has been an attacking force for Everton. He provides great pace, positioning and crossing ability when he joins the attacking play.

Also like Cole, Baines is a very sound defender. He's not the best, but he has good positioning and rarely puts his team in trouble on the defensive end.

It's easy to see, though, that his worth comes in offense. In addition to his great crossing, Baines adds a bit of set-piece flair to his arsenal.

While he wouldn't see much of that at Real, not as long as Cristiano Ronaldo is around to take free kicks, it's an extra dimension to his game that is worth praise.

Manchester United are currently pushing hard to seal a deal for the England international, but nothing has materialized.

Everton is in position to compete for European spots in the Premier League this season, so it's doubtful they would let Baines go unless it was above market value or with a player as part of a package.

Madrid is no stranger to opening the bank, but they might be skeptical to do so here. If they can find a way, though, Baines would be worth it.

4. Jose Enrique

Chris Brunskill/Getty ImagesIf Jose Enrique could find consistency, then he'd be a great choice

Jose Enrique's name may not bring excitement to anybody, but the Spanish defender was actually linked with a move to the Bernabeu (metro.co.uk) before he joined Liverpool from Newcastle.

In his short time at Anfield, Enrique has been good but not great. His most notable moment may be recently scoring his first goal with the Reds. And it was only notable because he was playing left-wing rather than his natural left-back.

Still, there's plenty to like about Enrique.

As evidenced by his ability to play up on the wing, he can handle the responsibilities of joining the attacking play. Enrique is also a very sound defender. He's strong and tough with enough pace that he can backtrack to defend the counter attack.

Like I mentioned earlier, that is something often missing from current footballers. The knock on Enrique, though, is consistency.

Madrid already have an inconsistent defender in Coentrao, who may also be a better player. Still, Coentrao hasn't found his consistency, and it's not out of the question to see him fall out of Real's plans just as easily as he has returned to them.

With Enrique fighting for a position on Brendan Rodgers' squad, he could be open to a move back home. Whether or not he'll be willing to take on a secondary role is the real question.